How to use conditional mock in Mockito

Question

I have a scala method call mocked in with mockito.

Let the object be a and method be b and the method b takes parameter of type Map[String, String]. I want to have a Map which meets a certain condition. I dont know all the key value pairs of this Map but I want to ensure that the Map has key value pairs like key1 -> value1 and key2 -> value2 when I use something like this

when(a.b(any[Map[String, String]])) thenReturn something

Here any is a static member in org.mockito. But I cant use this in here as this mock is satisfied for Map with any key and value. How to achieve a conditional mock in this case ??

I am looking for a utility which is analogous to where method which is in org.scalamock.matchers.Matchers

Answer 1

Try answers from IdiomaticMockito like so

import org.scalatest._
import org.mockito.{ArgumentMatchersSugar, IdiomaticMockito}

trait Foo {
  def bar(m: Map[String, String]): String
}

class FooSpec extends FlatSpec with Matchers with IdiomaticMockito with ArgumentMatchersSugar {
  "Foo object" should "say woohoo" in {
    val foo = mock[Foo]
    foo.bar(*) answers ((m: Map[String, String]) => if (m.exists(_ == ("key1", "value1"))) "woohoo" else "boom")
    foo.bar(Map("key1" -> "value1")) should be ("woohoo")
  }
}

Here we pass a conditional response to answers like so

if (m.exists(_ == ("key1", "value1"))) "woohoo" else "boom")

Note we use mockito-scala which is vanilla Mockito in addition to being aware of Scala specifics:

libraryDependencies += "org.mockito" %% "mockito-scala" % "1.5.11"

Here is the same solution with vanilla Mockito

import org.scalatest._
import org.mockito.Mockito
import org.mockito.Mockito._
import org.mockito.ArgumentMatchers._

trait Foo {
  def bar(m: Map[String, String]): String
}

class FooSpec extends FlatSpec with Matchers {
  "Foo object" should "say woohoo old syntax" in {
    val foo = Mockito.mock(classOf[Foo])
    doAnswer({ args =>
      val m = args.getArgument[Map[String, String]](0)
      if (m.exists(_ == ("key1", "value1"))) "woohoo" else "boom"
    }).when(foo).bar(any[Map[String, String]])

    foo.bar(Map("key1" -> "value1")) should be ("woohoo")
  }
}